Use PassiveObject were possible.

runtime/vm/debugger.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 1953 matching lines @@
 
 // TODO(hausner): Merge some of this functionality with the code in
 // dart_api_impl.cc.
 RawObject* Debugger::GetInstanceField(const Class& cls,
                                       const String& field_name,
                                       const Instance& object) {
   const Function& getter_func =
       Function::Handle(cls.LookupGetterFunction(field_name));
   ASSERT(!getter_func.IsNull());
 
-  Object& result = Object::Handle();
+  PassiveObject& result = PassiveObject::Handle();
   bool saved_ignore_flag = ignore_breakpoints_;
   ignore_breakpoints_ = true;
 
   LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, object);
     result = DartEntry::InvokeFunction(getter_func, args);
   } else {
     result = isolate_->object_store()->sticky_error();
@@ skipping 16 matching lines @@
   }
   // There is no field or the field has not been initialized yet.
   // We must have a getter. Run the getter.
   const Function& getter_func =
       Function::Handle(cls.LookupGetterFunction(field_name));
   ASSERT(!getter_func.IsNull());
   if (getter_func.IsNull()) {
     return Object::null();
   }
 
-  Object& result = Object::Handle();
+  PassiveObject& result = PassiveObject::Handle();
   bool saved_ignore_flag = ignore_breakpoints_;
   ignore_breakpoints_ = true;
   LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     result = DartEntry::InvokeFunction(getter_func, Object::empty_array());
   } else {
     result = isolate_->object_store()->sticky_error();
   }
   ignore_breakpoints_ = saved_ignore_flag;
   return result.raw();
 }
 
 
 RawArray* Debugger::GetInstanceFields(const Instance& obj) {
   Class& cls = Class::Handle(obj.clazz());
   Array& fields = Array::Handle();
   Field& field = Field::Handle();
   const GrowableObjectArray& field_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New(8));
   String& field_name = String::Handle();
-  Object& field_value = Object::Handle();
+  PassiveObject& field_value = PassiveObject::Handle();
   // Iterate over fields in class hierarchy to count all instance fields.
   while (!cls.IsNull()) {
     fields = cls.fields();
     for (intptr_t i = 0; i < fields.Length(); i++) {
       field ^= fields.At(i);
       if (!field.is_static()) {
         field_name = field.name();
         field_list.Add(field_name);
         field_value = GetInstanceField(cls, field_name, obj);
         field_list.Add(field_value);
       }
     }
     cls = cls.SuperClass();
   }
   return Array::MakeArray(field_list);
 }
 
 
 RawArray* Debugger::GetStaticFields(const Class& cls) {
   const GrowableObjectArray& field_list =
       GrowableObjectArray::Handle(GrowableObjectArray::New(8));
   Array& fields = Array::Handle(cls.fields());
   Field& field = Field::Handle();
   String& field_name = String::Handle();
-  Object& field_value = Object::Handle();
+  PassiveObject& field_value = PassiveObject::Handle();
   for (intptr_t i = 0; i < fields.Length(); i++) {
     field ^= fields.At(i);
     if (field.is_static()) {
       field_name = field.name();
       field_value = GetStaticField(cls, field_name);
       field_list.Add(field_name);
       field_list.Add(field_value);
     }
   }
   return Array::MakeArray(field_list);
 }
 
 
 void Debugger::CollectLibraryFields(const GrowableObjectArray& field_list,
                                     const Library& lib,
                                     const String& prefix,
                                     bool include_private_fields) {
   DictionaryIterator it(lib);
   Object& entry = Object::Handle(isolate_);
   Field& field = Field::Handle(isolate_);
   String& field_name = String::Handle(isolate_);
-  Object& field_value = Object::Handle(isolate_);
+  PassiveObject& field_value = PassiveObject::Handle(isolate_);
   while (it.HasNext()) {
     entry = it.GetNext();
     if (entry.IsField()) {
       field ^= entry.raw();
       ASSERT(field.is_static());
       field_name = field.name();
       if ((field_name.CharAt(0) == '_') && !include_private_fields) {
         // Skip library-private field.
         continue;
       }
@@ skipping 489 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart